If you have downloaded the project template for Flashdevelop: http://blubl.geoathome.at/wp-content/uploads/2010/10/091-ActionScript-3-Android-AIR-AS3-Projector.zip
… put it in the flashdevelop/projects folder. Now you can select Android/Air app in the “new project”-screen. The template contains a good readme.txt for what you need to do.
Additionally you have to setup the compiler options and setup the custom path to Flex SDK. Also start adl.exe with the parameter -runtime to lookup the version of it. If it says 2.6 you have to change the application.xml accordingly.
Otherwise adl will quit its job telling you: Error while loading initial content. Now you should be able to test you apps in FlashDevelop.
Changing Screen Size
If you want to change the screensize in which adl opens your app go to project settings and edit “run custom command”. Change it to:
$(FlexSDK)\bin\adl.exe; -screensize 600×1024:600×1024 application.xml bin
The second resolution is for fullscreen mode and needs to be set for adl to work.